U.S. Pat. No. 3,839,444 describes herbicidal compounds having the formula ##STR2## wherein X is halogen,
n is 1 to 5, and PA1 R is amido, alkylamido (C.sub.1 -C.sub.4) or dialkylamido (C.sub.3 -C.sub.4). PA1 R.sub.1 is methyl or ethyl; PA1 R.sub.2 is alkyl of 1-4 carbon atoms, methoxy or cyanomethyl; and PA1 R.sub.1 and R.sub.2 together can be (CH.sub.2).sub.4 ; provided that when R.sub.2 is alkyl of 3 or 4 carbon atoms, methoxy or cyanomethyl, R.sub.1 cannot be ethyl.
German Offenlegungsschrift No. 2,619,489 discloses compounds such as 3-Dimethylcarbamoyl diphenylether.
U.S.S.R. 209,445 describes the acylation of diphenylether with dimethylcarbamoyl chloride in the presence of aluminum chloride.
Although the abstract does not specify the position of the dimethylcarbamoyl group in the resulting product, it can be deduced that the resulting product is N,N-dimethyl-p-phenoxybenzamide.
Compounds such as those taught in U.S. Pat. No. 3,839,444 are active herbicides; the need still exists, however, for herbicides which are more active and more selective. The presence of undesired vegetation is very damaging to useful crops such as rice. In the current world situation, wherein food shortages are acute, it is most important not to lose a significant portion of a valuable crop such as rice. The presence of such undesired vegetation results in the loss of a significant portion of such crop. Thus, a need exists for a particularly effective herbicide which will destroy as much of this unwanted vegetation as is possible without causing significant damage to the desired crops, e.g., rice.
According to the instant invention, herbicidal compounds have been discovered which are highly active herbicides and yet cause minimal damage to certain desired crops.